Combustion control



July 30, 1940. R. E.' BRESSLER COMBUSTION CONTROL Filed Dec. '7, 1939 Patented July 30, 1940 UNITED STATES COMBUSTION CONTROL Robert E. Bresslcr, Oregon, 111., assignor to Kol- Master Corporation, Oregon, 111., a corporation of Illinois Application December 7, 1939, Serial No. 308,004

4 Claims.

This invention relates to improvements in combustion controls and it consists of the matters hereinafter described and more particularly pointed out in the appended claims.

The improved control is especially adapted for use in connection with stokers' of the underfeed type, suchas are used in connection with the furnaces for heating.

It must be borne in mind that the average owner of a stoker-equipped home knows little, if anything, of how or why a stoker functions automatically. Therefore, the owner is not only incapable of making adjustments thereon but is incapable of meeting any emergency should the stoker stop functioning as intended, as for example should the fire go out. Should the fire go out in the retort of such a stoker, when the usual controlling thermostat still calls for heat,

the fuel is continuously fed into the furnace and the result is often disastrous. Under such conditions the furnace usually fills up with fuel causing the fuel door to open so that the fuel spills out on the fioor. However should the door fail to open, the result might be that the furnace would be lifted off its setting. If, for any other reason, a great excess of fuel is fed to the retort, thesame result would obtain.

One of the objects of the present invention is to provide a combustion control which, if the air being supplied during a burning period is not sufficient in volume for the fuel being supplied, or if the fuel being supplied is more than is necessary for efficient combustion, or if the fire goes out and the fuel feed continues, will stop the stoker completely until the condition that caused the stoppage is rectified.

Another object of the invention is to provide a combustion control whereby it is possible after a stoker stoppage, to use the air supplying means in connection with the restarting of the fire, independently of the fuel feeding means, to support the combustion of the fuel bed until more fuel is necessary therefor and may be fed thereto, after which the stoker will find its balance between the fuel and air supplied and will then function automatically under the control of its associated thermostat.

Also, it is an object of the invention to provide a control of such simplicity that it may be readily manipulated even by an inexperienced stoker user to restart the fire after an out period.

Again, it is an object of the invention to pro- -vide a combustion control especially advantageous in connection with a bin-fed stoker or a stoker having a large capacity hopper to stop the stoker completely in case of an out fire and thus prevent the continued feeding of the fuel from the bin or hopper and the flooding or overfeed of fuel with attending disastrous results.

stoker structure appearing in Figs. 1 and 2.

Referring now in detail to that embodiment of the invention illustrated in the drawing, the stoker with which the improved control is employed includes, as best shown in Figs. 1 and 2, a burner 5, a hopper B, and a means 1 whereby fuel is fed from the hopper to the burner. Said stoker also includes a blower 8 for supplying the necessary air under pressure, a duct 9 for conveying the air under pressure to the burner and a motor I which, in this instance drives both the fuel feedin means and the blower.

The burner comprises a hollow windbox H in which a retort I2 is located in suitable relation to provide a chamber in said windbox surrounding the retort, said windbox having an air inlet at its front bottom end connected tothe duct 9. At the top of the windbox is a dead plate l3 and arranged between the inner margin of the dead plate and the top of the retort are the tuyres 14 whereby air under pressure is admitted from the windbox to the fuel bed for combustion purposes. I 40 The fuel feeding means 1 before mentioned includes a feed tube section I5 between the rear end of the lower portion of the hopper 6 and the fuel inlet opening of the burner and a second tube section Hi. The last mentioned section is in axial alignment with the first mentioned one and is arranged between the front end of the lower portion of the hopper 6 and the rear side of an upright casing l'l located in front 50 of the hopper. In the tube sections l5 and IE, which in this instance are disposed in the longitudinal median line of the hopper B, is located a feed screw I8. Said feed screw includes a shaft l9 and a flight thereon of a diameter approxi- 55 mating that ofthe inside diameter of the tube sections i5 and I6.

said

The feed screw it extends from casing ll end of the shaft I9 of the feed screw i8 arranged in the casing "and in the top end of said casing is journalled a transverse shaft 22 that appears in dotted lines in Fig. 2. This shaft carries a worm 23 which meshes with the worm gear 2! fixed to the feed screw. shaft as before described. The right hand end of the shaft 22 as appears in Fig. 2 extends outwardly beyond the associated side of the casing l1 and there has fixed to it a plurality or a set of stepped pulleys24-25 and 26 respectively. These pulleys successively increase in diameter outwardly from the associated side of the casing.

At the top portion of the casing i1 is a forward ly extending shelf Ila (see Figs. 1 and 2) and dependingl supported from the underside thereof, forward}; of the casing i1 is the electric motor ill. This motor includes an armature'shaft 28, opposite end portions of which proect beyond opposite ends of the motor. The right hand end of said shaft has a plurality or a set of stepped pulleys 29-30 and 3| respectively, fixed thereon and which successively decrease indiameter outwardly from the associated and of the motor. The pulleys in one set are arranged in the planes of the pulleys of the other set and a belt 32 is provided to drive onepulley in one set from an associated pulley in the other set. By changing the belt from one pair of associated pulleys in both sets thereof to another pair of associated pulleys thereof, it is possible to provide a number of different speed ratios of the drive between the motor I0 and the shaft 22. It is of course apparent that this change of speed ratios between said motor and said shaft maybeobtained through other means than the sets of pulleys and associated'belt. The latter, however, is illustrated and described as substantially the simplest; arrangement by which this change in speed ratios may be obtained. Also, it is apparent that should the motor ill be in operation, the drive for the feed screw i8 may be disconnected therefrom and reconnected thereto by removing and replacing the belt 32.

The left hand end offthe armature shaft extends into the blower casing 8 where it has fixed to it a rotor or fan of any desired typebut not shown herein; The left hand side of the blower casing, as viewed in Fig. 2 is provided with the usual air inlet-opening (not shown).

The air duct 9 connects the discharge side of the blower B with the inlet of the windbox H and this duct is arranged in a plane below that of the hopper 6 so as to pass beneath the same.

On thetop side of the shelf I'Ia is located a control or pressure switch indicated as a whole by the numeral 33, the construction of which best appears in Fig. 3. It includes a diaphragm casing comprising top and bottom, oppositely face; ing casing parts 36 and 35 respectively, each having an outwardly extending radial marginal flange. A flexible diaphragm 35 isclamped at its, peripheral margin between the marginal flanges of the casing parts at and 35. Rigid discs 31 are secured to opposite sides of the diaphragm 36 by means of an axially disposed upwardly extending stem 38 and associated nuts. The stem passes through an axial hole in the top casing aeoa'soc 'may be moved into this last part 35. The bottom of the diaphragm casing is connected to the duct 9'by a tube 39 and whereby substantially the same pressure is present in the casing below the diaphragm 36 as exists in said duct. i

The switch 33 ,also includes a switch casing 40 arranged in spaced relation above the diaphragm casing and on the bottom wall thereof is located a'fixed contact ll (see Fig. 3). 52 indicates a lever that is pivoted at one end in the casing 40 and carries a contact 43 at its other end for a make and break engagement with the fixed con- -tact. A spring 64 is fixed at one end to the casing in the plane of the pivotal connection for the lever, and is fixed at its other end to the lever at a point between its ends. This lever 42 is so arranged that when it is in a position wherein its contact 43 engages the contact 4|, the mid portion thereof is substantially engaged by the top end of the stem- 38. In the present instance the weight of the diaphragm 36 is intended to be more than the air pressure in the windbox II and duct 9 will lift at maximum pressure. Therefore, as shown herein lock nuts 45 are provided on the stem 38 above'the diaphragm and a spring 46 surrounds the stem between the diaphragm casing and nuts 65 to assist the diaphragm in lifting the lever 42 to disengage its contact from the contact 4|.

When the stem 38 has lifted the lever 42 past the horizontal position, the spring 44 will function to swing said lever up against a stop 41 appear, so that the stem 38 descends to a position permitting the lever 42 to be moved to engage its contact #3 with the contact 4| said lever mentioned position by the following means.

68 indicates a plunger that is arranged for a sliding movement through the top wall of the casing 40 .substantially in line with the stem 38 and in the vertical plane of the lever 42. The top end of this plunger is provided with a head 49 and a spring 50 surrounds that part of the plunger between its head 49 and the top wall of the casing and this spring functions normally to urge the plunger 48 upwardly. When the stem 38 is out of the way, a pressure on. the head end of the plunger 48 will depress the-lever 32 and swing it through the horizontal plane of its pivoted end when the spring 56 will act to swing the lever into a position wherein its contact 43 engages the contact d9.

In Fig. 3 is illustrated one form of control circuit for use in connection with the apparatus heretofore described. Said circuit includes a temperature responsive device 5! in the nature of a room thermostat 5!, a limit control 52, a transformer 53, a relay coil 5d and associated armature 55. The thermostat 5] is usually located in the room or space being heated and the limit control 52, which is associated with the furnace with which the stokerstructure is employed, normally functions as a closed switch.- The transformer 53 includes the primary and secondary windings 5S and 57.

58 and 59 indicate the main current conductors leading from a suitable source of electric current supply. 'Ihe' conductor 58 leads into one side of the limit control and a line til leads out of the other side of said control to a contact at and with which the armature is associated. A line 62 connects the armature 55 to the lever 42 and a line 63 connects the contact 4| with one side of the motor III, the other side .of said motor being connected to the conductor 59. When the armature 55 is engaged with the contact 6|, un-

der the. control of the thermostat 5|, the motor I0 is energized, assuming of course that the limit control 52 is functioning as a closed switch within its operative range. When the armature 55 is out of engagement with the contact 6|, the motor In is deenergized. I

The opposite ends of the primary winding 56 of the transformer 53 are normally connected by lines 58a and 59a to the lines 58 and 59 respectively. One end of the secondary winding of the transformer 53 is connected to one side i of the thermostat 5| by a line 64 and the other side of said secondary winding is connected by a line 65 to one side of the coil of the relay 54.

The other side of the thermostat is connected by a line 66 to the otherside of said coil 54.

A branch line 61 is provided between the lines 62 and 63 and in said branch line is a manually operable, normally open switch 68. A transformer 69 has its primary winding I0 connected to the lines 62 and 63 and has its secondary winding H connected to opposite sides of an audible signal 12 which is shown herein as a bell.

Assume that after astandby period, the contacts 4| and 43 are engaged and that the thermostat 5| calls for heat so as to energize the relay coil 54 to attract its armature 55 and engage it with the contact 6|. This will close the circuit from. the conductor 58 through the limit control 52, line to line 52, lever 42, contacts 43 and 4| to line 63 and through the motor Hi to the conductor 59. As the motor I0 is now energized, it will drive the feed screw I8 to feed fuel to the retort and will drive the blower 8, to provide a volume of air under pressure through the duct 9 to the retort so as to support the combustion of the -fuel bed. i

The amount of air delivered by the blower ordinarily will be suflicient to burn all the fuel fed by the screw I8 and by reason of the condition of the fuel bed, the pressure of the air in the duct being insufiicient to actuate the diaphragm 3? to cause the lever 42 to be moved to its open position. Under ordinary conditions, the stoker will function to deliver fuel and proportioned air to the retort until the thermostat 5i is satisfied as to temperature. At that time, the thermostat will break the circuit to the relay coil 54 so that 55 it becomes deenergized. The armature 55 then moves out of engagement with the contact 6| thus opening the circuit for the motor i0 which becomes deenergized and stops driving the feed screw and the blower.

Assuming that during a period of stoker operation when the thermostat is still calling for heat, some failure occurs so that either a greater amount'of fuel is fed to the stoker than the stoker will burn or that the fire goes out. Under either condition just mentioned, the resistance to the passage of air through the fuel bed will cause an increase in windbox pressure and which increase 'will be felt in the diaphragm casing below the diaphragm by reason of the tube 39. When this pressure becomes excessive, it will cause the diaphragm 36 to flex upwardly so that its associated stem 38 will engage the lever 42 and swing it through the horizontal plane of itspivoted end, after which the spring 44 will swing said lever into the full line position shown in Fig. '3 so that the contact 43 is disengaged from the contact 4|.

This, of course, will open the circuit to the motor which stops, so that no more fuel and air is fed to the burner. When the motor circuit is thus opened, and with the thermostat 5| still calling for heat, the transformer 69 becomes energized to sound the signal I2 but the current load passing through the transformer is not enough to operate the motor. When the signal is thus sounded, the' useris notified that the stoker has stopped with the thermostat still calling for heat.

. To restart the stoker, a source of combustion is applied to the fuel bed to start it burning again. Either before or after the fuel bed has been thus kindled, the operator removes the belt 32 from the pulleys about which it was trained so as to operatively disconnect the feed screw I3 from the motor i l]. Thereafter the operator actuates the manual switch 68 so as to close the circuit for the motor l0 therethrough, and this is independently of the switch 33 as a whole. When the switch 68 is thus closed, no appreciable current passesthrough the transformer 69 so that the signal 12 stops. When the motor is thus energized, it drives the blower 8 to supply the amount of air which will sustain combustion of the fuel bed, which at this time is relatively high. After the fuel bed has a good burning start, the operator depresses the plunger to throw the lever-42 into a position wherein its contact 43 is engaged with the contact 4|.

If at the time that the operator depresses the' plunger the fuelbed has not burned down sufficiently, then the excessive pressure in the windbox and below the diaphragm 35 will hold the stem 38 in its up position so that it prevents the lever 42 from moving into its circuit closing position. If the fuel bed has burned down sufficiently, it is apparent that the air being fed to the fuel bed meets a reduced resistance so that the pressure in.the duct 3, and against the bottom side of the diaphragm, will permit the diaphragm. to move towards its normal position so as to cause the stem 38 to move out of its position preventing or barring the movement of the lever. Thus when the operator again depresses the plunger M3, the lever42 is actuated to engage the contact 43 with the contact 4i and restore tbe circuit for the motor Id through the switch 33 as a whole.

Thereafter the operator opens the manual switch 63 and replaces the belt upon the proper pulleys of the sets of pulleys before mentioned.

This operation again connects the feed screw l8.

to the motor it so that it functions to feed fuel to the fuel bed on the retort. The stoker thereafter functions under the control of the thermostat as before.

It is apparent that the improved control forms a safety device for the stoker which may never be called into operation for its intended purpose, but which, if occasion should arise, may be readily brought into operation for its intended purpose. The device is especially valuable where the fuel is being fed to the retort from a bin or large hopper, because should the fire go out there is no possibility o'f the feeding that amount of fuel to the furnace as will discharge through the fire door should the same be pressed open or damage the furnace should the fire door, for some reason, fail to open.

While in describing the invention I have referred in detail to the form, arrangement and construction of parts, as well as the operation thereof, the same is to be considered only in the illustrative sense so that I do not wish to be limited thereto except as may be specifically set forth in the appended claims.

' I claim as my invention:

air delivering means from said-power means, an

electric circuit for said power means including a switch responsive to a relatively high pressure condition of the delivered air for opening said circuit to stop said power means, manually operable means for closing said circuit independently of said switch to restart said-power means for driving said air supplying means after said fuel feeding means has been disconnected from said power means, and a second manually operablev means for actuating said switch at a'lower pressure condition of the delivered air to close said circuit for maintaining said power means in operation after said first mentioned manually operable means has been actuated to open said circuit therethrough.

2. In combination with a retort for supporting a fuel bed, means for feeding fuel to the retort to provide a fuel bed thereon, means for de-q livering air to the fuel bed to supportcombustion thereof and which bed offers a resistance to the passage -.of air therethrough so that the pressure of said.air varies with the depth of the fuel bed, power means, means operable to connect said fuel feeding means to or to disconnect the same from said power means, means for driving said air delivering meansfrom said power means, an electric circuit for said power means including a swtich responsive to a relatively high pressure condition of the'delivered air for opening said circuit to stop said power means, a signal device in said circuit and operative when the circuit has been opened through said switch to indicate this condition of the circuit, manually operable means for closing said circuit independently of said switch to restart said power means for driving said air supplying means, after said fuel feeding means has-been disconnected from said power means, and a second manually operable means for actuating said switch at a lower pressure condition of-the delivered air to closesaid circuit for maintaining said power aaoaaoc meansinoperation after said first mentioned -manually operable means has been actuated to open said circuit therethrough.

3. In combination with a retort for supplying fuel bed, means for feeding fuel to the retort to providea fuel bed thereon, a blower for delivering air to the fuel bed to support combustion thereof and which bed offers a resistance'to the passage of air therethrough so that the pressure of said air varies with the depth of the fuel bed, a motor driving said blower direct, means operable to connect said fuel feeding means to or to disconnect the same from said, motor, a circuit for said motor, a, switch in and normally holding said circuit in a closed condition, means responsive to a relatively high pressure condition of the air delivered by the blower to actuate said switch to open said circuit and stop said motor, manually operative means for closing said circuit after it has been opened by said switch so as to restart said motor after the fuel feeding means.

has been disconnected from said motor, and a second manually operable means for actuating said switch at a lower pressure condition of the delivered air for closing said circuit for maintaining said motor in operation after said first I mentioned manually operable means has been actuated to open said circuit therethrough.

i. In combination with a retort for supporting afuel bed, means for feeding fuel to the retort to provide a fuel bed thereon, a blower for delivering air to the fuel bed tosupport combustion thereof and which bed offers a resistance to the passage of air therethrough so that the pressure of said air varies with the depthoof the fuel bed, a motor driving said blower direct, means operable to connect said fuel feeding means to or to disconnect the same from said motor, a circuit for said'motor, a switch in and normally holding said circuit in a closed condition, means reconnected from said motor, and a second manually operable means for actuating said switch at a lower pressure condition of'the delivered air for closing said switch to maintainsaid motor in operation after said first mentioned manually operable means has been actuated'to open said ":ircuit therethrough.

' ROBERTE. BRESSLER. 

